Safety device for vehicle occupants

ABSTRACT

A safety device for preventing injury to vehicle occupants upon the occurrence of a collision. The device includes an inflatable bag, a source of gas for rapidly inflating the bag, a triggering mechanism for actuating the gas source and an exhaust vent in communication with the bag interior for venting inflation gases from the bag in a controlled manner. Venting may be concurrent with the inflation process, or may be delayed by use of a valve openable at a predetermined pressure or by initially sealing the vent inlet with a combustible, solid fuel element that allows gas to escape through the vent after a period of combustion. The same fuel element also constitutes the gas source of the device.

United States Patent [1 1 Goes et al.

[ SAFETY DEVICE FOR VEHICLE OCCUPANTS {75] Inventors: Friedrich Goes,Wolfsburg; Ulrich Seiffert; Dieter Hinzmann, both of Braunschweig;Gunnar Borenius, Fallersleben, allof Germany [73] Assignee:Volkswagenwerk Aktiengesellschaft,

Wolfsburg, Germany [22] Filed: Nov. 1, 1971 [21] Appl. No.: 194,717

[30] Foreign Application Priority Date Nov. 14, 1970 Germany P20 56-101.7

[56] References Cited UNITED STATES PATENTS 3,622,176 ll/l97l Byer280/150 AB [451 July 24,1973

3,638,964 2/1972 Chute 280/150 AB Primary Examiner-Kenneth H. BettsAssistant Examiner-John P. Silverstrim Attorney-Granville M. Brumbaugh,Ronald B. Hildreth et al.

57 ABSTRACT A safety device for preventing injury to vehicle occupantsupon the occurrence of a collision. The device includes an inflatablebag, a source of gas for rapidly inflating the bag, a triggeringmechanism for actuating the gas source and an exhaust vent incommunication with the bag interior for venting inflation gases from thebag in a controlled manner. Venting may be concurrent with the inflationprocess, or may be delayed by useof a valve openable at a predeterminedpressure or by initially sealing the vent inlet with a combustible,solid fuel element that allows gas to escape through the vent after aperiod of combustion. The same fuel element also constitutes the gassource of the device.

6 Claims, 4 Drawing Figures PAIENIEU JUL 24 I975 Fig.4

Fig. 3

Fig. 2

SAFETY DEVICE FOR VEHICLE OCCUPANTS BACKGROUND OF THE INVENTION Thisinvention relates generally to safety devices for protecting theoccupants of vehicles against injuries due to collisions, andparticularly concerns a vehicular safety device of this type in which arapidly inflatable bag is utilized to prevent an occupant from beingthrown against the vehicle structure.

Various forms of inflatable bag safety devices of the kind referred tohave been developed in the past. West German patent No. 1,264,275, forexample, describes one such prior art device. However, these deviceshave not proven to be entirely satisfactory, chiefly because of therelatively uncontrolled manner in which the bags are inflated and theresulting lack of a dampened, pro.- longed cushioning action at the timeof and following the initial collision. Such devices are thereforeespecially ineffectual in preventing injuries from secondary accidents,which often accompany overturning or multiple-vehicle chain reactioncollisions and which require prolonged protection for the occupant.

Bursting of the bags upon impact, with consequent release of noxious oreven toxic gases to the vehicle interior, is also a problem with theforegoing prior art equipment. Efforts directed toward overcoming thisdeficiency have included the provision of pressure equalizing chambersin conjunction with the impactabsorbing bag, as in the system disclosedin West German patent No. l,280,072,but this approach fails to providecushioning action of the nature or duration required for full occupantsafety.

SUMMARY OF THE INVENTION It is an object of the invention, therefore, toprovide an impact-absorbing safety device for vehicle occupants whichwill fully absorb the initial impact of an occupant upon the occurrenceof a collision and thereafter will continue to cushion the occupant fora prolonged period to protect him against injuries from secondaryaccidents.

Another object of the invention is to provide an inflatable safetydevice for use in vehicles that will inflate very rapidly following acollision to prevent an occupant from being thrown against the vehiclestructure and which subsequently will collapse in a slow, controlledmanner to provide a sustained dampened cushioning effect on theoccupant.

A further object of the invention is to provide a safety device of thekind described in which the inflatable bag is protected against burstingon impact of the occupant therewith and in which noxious gases containedwithin the bag are vented to the exterior of the vehicle.

These objects, together with other objects and advantages that willbecome apparent hereinafter, are achieved, in accordance with theinvention, by a vehicular safety device which includes an inflatablebag, a source of gas for rapidly inflating the bag, a collision sensingdevice for triggering the gas source when a collision occurs and aprovision for controllably venting the bag either concurrently with orimmediately following the impact of an occupant against the bag. Suchventing of the inflation gases permits the bag to absorb the shock ofimpact in a gradual manner and thereby provide a softer, less resilientsurface for receiving the occupant. It also arrests the subsequent.collapse of the bag so as to afford prolonged protection againstinjuries resulting from secondary accidents. In addition, by relievingoverpressure within the bag, venting greatly reduces the likelihood ofthe bag bursting when an occupant is thrown against it. As a furtheradvantage, the inflation gases, which may be noxious or perhaps eventoxic depending on the gas source used, are prevented from reachingoccupied areas of the vehicle, but are instead discharged to the vehicleexterior.

In one embodiment of the invention, the venting structure is equippedwith a normally closed valve, which opens upon the bag pressure reachinga predetermined minimum. Alternatively, the vent may simply be left openat alltimes. In either case, the bag is very rapidly filled immediateyafter a collision, and then slowly collapses as the gases escape fromthe bag.

According to another embodiment, a solid fuel element of the type whichgenerates gas upon combustion is positioned in sealing relation acrossthe vent inlet. Gas escape from the bag is therefore prevented by thefuel element until a sufficient amount of the element has been burnedaway to clear the inlet. The time required for the vent to become clear,and hence for venting to begin, may be controlled by varying thethickness of the portion of the fuel element overlying the vent inlet.

BRIEF DESCRIPTION OF THE DRAWINGS For 'a better understanding of theinvention, reference may be made to the following description ofexemplary embodiments, taken in conjunction with the figures of theaccompanying drawings, in which:

FIG. 1 is a cross sectional view of an embodiment of a safety deviceconstructed in accordance with the invention, showing one arrangementfor venting the impactbag; and

FIGS. 2, 3 and 4 are cross sectional views of other venting arrangementsaccording to the invention.

DESCRIPTION OF EXEMPLARY EMBODIMENTS As illustrated in FIG. 1, arepresentative embodiment of the impact-cushioning safety device 2 ofthe invention is adapted to be mounted on any suitable supportingsurface 1 of a vehicle. In land vehicles the supporting surface 1 mightconstitute, for example, the dashboard, roof, seat backs or doors of thevehicle, while in aircraft the surface 1 could be constituted byappropriate parts of the seats, fuselage, partitions or the like. Thesafety device 2 may of course be installed in other types of vehicles,and at locations other than those referred to above.

The safety device 2, as depicted in FIG. 1, includes a protective,frangible housing 3 which encloses an inflatable bag 4, a solid fuelelement 5 and a powder-type primer 6. Upon the occurrence of acollision, the primer 6 is triggered by a collision sensing device (notshown) of conventional design, thereby igniting the fuel element 5. Onceignited, the element 5 generates gas extremely rapidly, inflating thebag 4 and rupturing the housing 3. r

Any one of several techniques, electrical, mechanical or pyrotechnical,may be employed to ignite the fuel element 5. For instance, the powderprimer 6 could be replaced by a mechanically or electrically actuateddetonator. Similarly, the invention is not limited to the use of a solidfuel which releases gases upon combustion,

but may instead utilize other sources of inflation gases, such as, forexample, a pressurized gas bottle.

As noted, it is a feature of the invention that the safety device 2 alsoincludes a provision for venting some of the inflation gases from theimpact bag 4. Various arrangements for accomplishing this are depictedin FIGS. 1 to 4, each of which includes a vent duct 7 that communicatesat one end 7a with the interior of the bag 4 and at the other end to thevehicle exterior.

According to the invention, the duct 7 may or may not be closed offduring the initial stage of the inflation process. Hence, in theembodiment pictured in FIG. 2, the duct 7 is left open at all times toprovide continuous venting of the bag. The gas generating element 5 islocated in surrounding relation to the duct 7, with the bag 4 extendingover the element 5 and a portion of the duct 7 to form a completelysealedenvelope except for the vent duct. Since during combustion thefuel element liberates a great deal more gas than can escape through theduct 7, the bag 4 will be inflated sufficiently to protect the occupantagainst being thrown against the vehicle structure, notwithstanding thatthe duct is always open. Concurrent inflating and venting of the bag inthis fashion allows the bag to absorb the shock of the initial impact bythe occupant gradually. This gives a softer, less resilient, cushioningeffect in response to the'primary collision, while also affordingsustained protection against secondary accidents as well.

The venting arrangement illustrated in FIG. 1, on the other hand, atfirst seals the duct 7 against gas flow by positioning the fuel element5 across its inner end 7a. No gas can escape from the bag 4, therefore,until enough of the fuel element has been burned away to clear the inletto duct. Preferably this would occur shortly after the occupant firstcontacts the inflated bag 4 following a collision, although the portionof the element 5 overlying the inner end 70 of the duct may be shapedand sized so as to clear the opening at a different time.

With the FIG. 1 configuration, the gas formed when the fuel element 5 isfirst ignited is utilized solely to achieve prompt inflation of the bag4. Then after some period of combustion and inflation, the vent'duct 7will become clear and venting of the inflation gases will begin. Thiscombines maximum impact protection at the first collision, continuedprotection against secondary accidents, and a dampened, yieldingcushioning action for greater occupant safety.

FIG. 3 depicts a venting arrangement incorporating features of both theFIG. 1 and the FIG. 2 embodiments, while adding still other features.The fuel element 5 originally blocks the vent duct 7, as in FIG. 1, butis grooved or hollowed out on the side away from the duct to provide aportion 8 of thinner cross section adjacent to the inlet end 70 of theduct. So shaped, the element 5 will burn clear of the inlet end 7asooner than in the FIG. 1 arrangement, with the result that venting willbegin at an earlier time in the inflation process. It will beappreciated that by varying the thickness of the portion 8 the time atwhich venting commences can be controlled. Inflation and collapse of thebag 4 will be much the same as with the embodiment of FIG.

The arrangement represented in FIG. 4 is generally similar to that ofFIG. 2-, except that a valve 9 is provided in the vent duct 7. The'valve9 is normally closed, and may be of the type including a spring member10 to urge it to the closed position. As the pressure within the bag 4builds up, the valve 9 will open allowing gas to escape through the duct7. Again, a gradual collapse of the bag is provided, with accompanyingslower absorbtion of impact forces for less rigid support of theoccupant and sustained protection against subsequent injuries.

Any one of the venting arrangements portrayed in FIGS. 2, 3 and 4 may beemployed with a frangible, protective housing 3 (see FIG. 1), and ofcourse may be mounted in any convenient manner and in any suitablelocation within a vehicle. I

It is another feature of the invention that not only is improvedprotection afforded vehicle occupants against injury from both primaryand secondary accidents, but at the same time failure of the safetydevice due to the bag bursting under the shock of an occupant beingthrown against it is substantially eliminated. Since the inflation gasesare vented either concurrently with or immediately after the firstcontact of the occupant with the bag, pressure relief is provided at themost crucial time insofar as the buildup of internal pressure beyond thebursting strength of the bag is concerned. Hence, there is littlelikelihood that a bag will burst in the midst of an accident due tooverpressure.

Additionally, the invention provides the further feature of venting theinflation gases to the vehicle exterior. This is particularlyadvantageous inasmuch as the gases released by solid fuels, and otherotherwise desirable gas sources as well, are often noxious andsometimes-even toxic in character. It is important, therefore, that theynot be permitted to reach occupied areas of the vehicle. Theinventionprevents this from occurring in two ways; one, by diminishing theprobability of the impact bag rupturing during an accident and, two, byventing the inflation gases to an exterior discharge.

It will be understood by those skilled in the art that theabove-described embodiments are intended to be merely exemplary, in thatthey are susceptible of modification and variation without departingfrom the inventive concepts disclosed. All such modifications andvariations, therefore, are included within the spirit and scope of theinvention as defined in the appended claims.

We claim:

1. A safety device for protecting vehicle occupants against injuryresulting from collisions, comprising:

a. an inflatable bag adapted to absorb the impact of an occupant whenthe bag is inflated;

b. a solid fuel element adapted to generate gas for inflating the bagupon ignition of the fuel element;

0. means for igniting the solid fuel element upon the occurrence of acollision; and

d. means defining a vent, having an inlet end in communication with thebag interior and an outlet end, for controllably venting at least aportion of the inflation gases from the bag in such a way as to allowthe bag to be rapidly inflated following a collision and thereafter togradually collapse to provide a dampened cushioning action to protectthe occupant during the collision and to afford continued protection forthe occupant against injury from secondary accidents, the initiation ofthe gradual collapse being controlled by placement of the solid fuelelement in sealing relation to the inlet end of the vent to prevent gasflow through the vent until the combustion of at least a portion of thesolid fuel element has occurred.

2. A safety device according to claim 1 wherein:

the solid fuel element is located in overlying relation to the inlet endof the vent; and

the portion of the fuel element overlying the inlet end is sized toallow the escape of gas therethrough after a predetermined time ofcombustion and inflation.

3. A safety device according to claim 2 wherein:

the solid fuel element is hollowed out'on the side thereof away from thevent inlet end so that the portion thereof overlying the vent inlet endis of reduced cross sectional thickness.

4. A safety device according to claim 1 wherein:

the solid fuel element is disposed across the inlet end to the exteriorof the vehicle.

1. A safety device for protecting vehicle occupants against injuryresulting from collisions, comprising: a. an inflatable bag adapted toabsorb the impact of an occupant when the bag is inflated; b. a solidfuel element adapted to generate gas for inflating the bag upon ignitionof the fuel element; c. means for igniting the solid fuel element uponthe occurrence of a collision; and d. means defining a vent, having aninlet end in communication with the bag interior and an outlet end, forcontrollably venting at least a portion of the inflation gases from thebag in such a way as to allow the bag to be rapidly inflated following acollision and thereafter to gradually collapse to provide a dampenedcushioning action to protect the occupant during the collision and toafford continued protection for the occupant against injury fromsecondary accidents, the initiation of the gradual collapse beingcontrolled by placement of the solid fuel element in sealing relation tothe inlet end of the vent to prevent gas flow through the vent until thecombustion of at least a portion of the solid fuel element has occurred.2. A safety device according to claim 1 wherein: the solid fuel elementis located in overlying relation to the inlet end of the vent; and theportion of the fuel element overlying the inlet end is sized to allowthe escape of gas therethrough after a predetermined time of combustionand inflation.
 3. A safety device according to claim 2 wherein: thesolid fuel element is hollowed out on the side thereof away from thevent inlet end so that the portion thereof overlying the vent inlet endis of reduced cross sectional thickness.
 4. A safety device according toclaim 1 wherein: the solid fuel element is disposed across the inlet endof the vent in sealing relation thereto, whereby gas flow through thevent is prevented by the fuel element until the combustion of at least aportion thereof.
 5. A safety device according to claim 1 furthercomprising: a frangible housing enclosing the bag and the gas sourcedefining means, the housing being rupturable bY the bag upon theinflation thereof.
 6. A safety device according to claim 1 in which theoutlet end of the vent defining means discharges the gas to the exteriorof the vehicle.